452 lines
11 KiB
JavaScript
452 lines
11 KiB
JavaScript
/*\
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title: $:/plugins/tiddlywiki/railroad/parser.js
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type: application/javascript
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module-type: library
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Parser for the source of a railroad diagram.
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x y z sequence
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<-x y z-> explicit sequence
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[:x] optional, normally included
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[x] optional, normally omitted
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{x} one or more
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{x +","} one or more, comma-separated
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[{:x}] zero or more, normally included
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[{:x +","}] zero or more, comma-separated, normally included
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[{x}] zero or more, normally omitted
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[{x +","}] zero or more, comma-separated, normally omitted
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(x|y|z) alternatives
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(x|:y|z) alternatives, normally y
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"x" terminal
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<"x"> nonterminal
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/"blah"/ comment
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- dummy
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[[x|"tiddler"]] link
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{{"tiddler"}} transclusion
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"x" can also be written 'x' or """x"""
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pragmas:
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\arrow yes|no
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\debug yes|no
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\start single|double|none
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\end single|double|none
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\*/
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(function(){
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/*jslint node: true, browser: true */
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/*global $tw: false */
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"use strict";
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var components = require("$:/plugins/tiddlywiki/railroad/components.js").components;
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var Parser = function(widget,source,options) {
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this.widget = widget;
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this.source = source;
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this.options = options;
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this.tokens = this.tokenise(source);
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this.tokenPos = 0;
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this.advance();
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this.content = this.parseContent();
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this.root = new components.Root(this.content);
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this.checkFinished();
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};
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/////////////////////////// Parser dispatch
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Parser.prototype.parseContent = function() {
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var content = [];
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// Parse zero or more components
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while(true) {
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var component = this.parseComponent();
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if(!component) {
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break;
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}
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if(!component.isPragma) {
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content.push(component);
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}
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}
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return content;
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};
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Parser.prototype.parseComponent = function() {
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var component = null;
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if(this.token) {
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if(this.at("string")) {
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component = this.parseTerminal();
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} else if(this.at("name")) {
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component = this.parseName();
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} else if(this.at("pragma")) {
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component = this.parsePragma();
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} else {
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switch(this.token.value) {
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case "[":
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component = this.parseOptional();
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break;
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case "{":
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component = this.parseRepeated();
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break;
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case "<":
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component = this.parseNonterminal();
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break;
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case "(":
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component = this.parseChoice();
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break;
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case "/":
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component = this.parseComment();
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break;
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case "[[":
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component = this.parseLink();
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break;
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case "{{":
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component = this.parseTransclusion();
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break;
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case "<-":
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component = this.parseSequence();
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break;
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case "-":
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component = this.parseDummy();
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break;
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}
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}
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}
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return component;
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};
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/////////////////////////// Specific components
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Parser.prototype.parseChoice = function() {
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// Consume the (
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this.advance();
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var content = [],
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colon = -1;
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do {
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// Allow at most one branch to be prefixed with a colon
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if(colon === -1 && this.eat(":")) {
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colon = content.length;
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}
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// Parse the next branch
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content.push(this.parseContent());
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} while(this.eat("|"));
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// Consume the closing bracket
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this.close(")");
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// Create a component
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return new components.Choice(content,colon === -1 ? 0 : colon);
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};
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Parser.prototype.parseComment = function() {
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// Consume the /
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this.advance();
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// The comment's content should be in a string literal
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var content = this.expectString("after /");
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// Consume the closing /
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this.close("/");
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// Create a component
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return new components.Comment(content);
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};
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Parser.prototype.parseDummy = function() {
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// Consume the -
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this.advance();
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// Create a component
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return new components.Dummy();
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};
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Parser.prototype.parseLink = function() {
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// Consume the [[
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this.advance();
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// Parse the content
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var content = this.parseContent();
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// Consume the |
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this.expect("|");
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// Consume the target
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var target = this.expectNameOrString("as link target");
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// Prepare some attributes for the SVG "a" element to carry
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var options = {"data-tw-target": target};
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if($tw.utils.isLinkExternal(target)) {
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options["data-tw-external"] = true;
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}
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// Consume the closing ]]
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this.close("]]");
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// Create a component
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return new components.Link(content,options);
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};
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Parser.prototype.parseName = function() {
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// Create a component
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var component = new components.Nonterminal(this.token.value);
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// Consume the name
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this.advance();
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return component;
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};
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Parser.prototype.parseNonterminal = function() {
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// Consume the <
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this.advance();
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// The nonterminal's name should be in a string literal
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var content = this.expectString("after <");
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// Consume the closing bracket
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this.close(">");
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// Create a component
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return new components.Nonterminal(content);
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};
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Parser.prototype.parseOptional = function() {
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var wantArrow = this.options.arrow;
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// Consume the [
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this.advance();
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// Consume the { if there is one
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var repeated = this.eat("{");
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// Note whether omission is the normal route
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var normal = this.eat(":");
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// Parse the content
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var content = this.parseContent(),
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separator = null;
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// Parse the separator if there is one
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if(repeated && this.eat("+")) {
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separator = this.parseContent();
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}
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// Consume the closing brackets
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if(repeated) {
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this.close("}");
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}
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this.close("]");
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// Create a component
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return repeated ? new components.OptionalRepeated(content,separator,normal,wantArrow)
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: new components.Optional(content,normal);
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};
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Parser.prototype.parseRepeated = function() {
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var wantArrow = this.options.arrow;
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// Consume the {
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this.advance();
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// Parse the content
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var content = this.parseContent(),
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separator = null;
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// Parse the separator if there is one
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if(this.eat("+")) {
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separator = this.parseContent();
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}
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// Consume the closing bracket
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this.close("}");
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// Create a component
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return new components.Repeated(content,separator,wantArrow);
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};
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Parser.prototype.parseSequence = function() {
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// Consume the <-
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this.advance();
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// Parse the content
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var content = this.parseContent();
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// Consume the closing ->
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this.close("->");
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// Create a component
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return new components.Sequence(content);
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};
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Parser.prototype.parseTerminal = function() {
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var component = new components.Terminal(this.token.value);
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// Consume the string literal
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this.advance();
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return component;
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};
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Parser.prototype.parseTransclusion = function() {
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// Consume the {{
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this.advance();
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// Consume the text reference
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var textRef = this.expectNameOrString("as transclusion source");
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// Consume the closing }}
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this.close("}}");
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// Retrieve the content of the text reference
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var source = this.widget.wiki.getTextReference(textRef,"",this.widget.getVariable("currentTiddler"));
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// Parse the content
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var content = new Parser(this.widget,source).content;
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// Create a component
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return new components.Transclusion(content);
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};
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/////////////////////////// Pragmas
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Parser.prototype.parsePragma = function() {
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// Create a dummy component
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var component = { isPragma: true };
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// Consume the pragma
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var pragma = this.token.value;
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this.advance();
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// Apply the setting
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if(pragma === "arrow") {
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this.options.arrow = this.parseYesNo(pragma);
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} else if(pragma === "debug") {
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this.options.debug = true;
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} else if(pragma === "start") {
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this.options.start = this.parseTerminusStyle(pragma);
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} else if(pragma === "end") {
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this.options.end = this.parseTerminusStyle(pragma);
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} else {
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throw "Invalid pragma";
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}
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return component;
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};
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Parser.prototype.parseYesNo = function(pragma) {
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return this.parseSetting(["yes","no"],pragma) === "yes";
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}
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Parser.prototype.parseTerminusStyle = function(pragma) {
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return this.parseSetting(["single","double","none"],pragma);
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}
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Parser.prototype.parseSetting = function(options,pragma) {
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if(this.at("name") && options.indexOf(this.token.value) !== -1) {
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return this.tokenValueEaten();
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}
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throw options.join(" or ") + " expected after \\" + pragma;
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}
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/////////////////////////// Token manipulation
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Parser.prototype.advance = function() {
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if(this.tokenPos >= this.tokens.length) {
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this.token = null;
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}
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this.token = this.tokens[this.tokenPos++];
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};
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Parser.prototype.at = function(token) {
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return this.token && (this.token.type === token || this.token.type === "token" && this.token.value === token);
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};
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Parser.prototype.eat = function(token) {
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var at = this.at(token);
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if(at) {
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this.advance();
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}
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return at;
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};
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Parser.prototype.tokenValueEaten = function() {
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var output = this.token.value;
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this.advance();
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return output;
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};
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Parser.prototype.close = function(token) {
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if(!this.eat(token)) {
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throw "Closing " + token + " expected";
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}
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};
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Parser.prototype.checkFinished = function() {
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if(this.token) {
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throw "Syntax error at " + this.token.value;
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}
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};
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Parser.prototype.expect = function(token) {
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if(!this.eat(token)) {
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throw token + " expected";
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}
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};
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Parser.prototype.expectString = function(context,token) {
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if(!this.at("string")) {
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token = token || "String";
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throw token + " expected " + context;
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}
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return this.tokenValueEaten();
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};
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Parser.prototype.expectNameOrString = function(context) {
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if(this.at("name")) {
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return this.tokenValueEaten();
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}
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return this.expectString(context,"Name or string");
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};
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/////////////////////////// Tokenisation
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Parser.prototype.tokenise = function(source) {
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var tokens = [],
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pos = 0,
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c, s, token;
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while(pos < source.length) {
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// Initialise this iteration
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s = token = null;
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// Skip whitespace
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pos = $tw.utils.skipWhiteSpace(source,pos);
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// Avoid falling off the end of the string
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if (pos >= source.length) {
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break;
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}
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// Examine the next character
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c = source.charAt(pos);
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if("\"'".indexOf(c) !== -1) {
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// String literal
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token = $tw.utils.parseStringLiteral(source,pos);
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if(!token) {
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throw "Unterminated string literal";
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}
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} else if("[]{}".indexOf(c) !== -1) {
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// Single or double character
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s = source.charAt(pos+1) === c ? c + c : c;
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} else if(c === "<") {
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// < or <-
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s = source.charAt(pos+1) === "-" ? "<-" : "<";
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} else if(c === "-") {
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// - or ->
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s = source.charAt(pos+1) === ">" ? "->" : "-";
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} else if("()>+/:|".indexOf(c) !== -1) {
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// Single character
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s = c;
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} else if(c.match(/[a-zA-Z]/)) {
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// Name
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token = this.readName(source,pos);
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} else if(c.match(/\\/)) {
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// Pragma
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token = this.readPragma(source,pos);
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} else {
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throw "Syntax error at " + c;
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}
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// Add our findings to the return array
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if(token) {
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tokens.push(token);
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} else {
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token = $tw.utils.parseTokenString(source,pos,s);
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tokens.push(token);
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}
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// Prepare for the next character
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pos = token.end;
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}
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return tokens;
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};
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Parser.prototype.readName = function(source,pos) {
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var re = /([a-zA-Z0-9_.-]+)/g;
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re.lastIndex = pos;
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var match = re.exec(source);
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if(match && match.index === pos) {
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return {type: "name", value: match[1], start: pos, end: pos+match[1].length};
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} else {
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throw "Invalid name";
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}
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};
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Parser.prototype.readPragma = function(source,pos) {
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var re = /([a-z]+)/g;
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pos++;
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re.lastIndex = pos;
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var match = re.exec(source);
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if(match && match.index === pos) {
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return {type: "pragma", value: match[1], start: pos, end: pos+match[1].length};
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} else {
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throw "Invalid pragma";
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}
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};
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/////////////////////////// Exports
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exports.parser = Parser;
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})(); |